Conventional reactor lockhoppers operate in a batch mode, causing significant loss of energy, both in pressurization and depressurization at each batch dumping, and concomitant heat loss from the system. In addition, the airlock valves, which close off the lockhopper, operate in an extremely hostile environment--hot and abrasive--which severely limits the life of the pressure seals and valves.
During each batch dump, a substantial amount of reactor vessel gases are released to the outside air. These are often hazardous toxic gases which must be scrubbed, or otherwise purified, before final release. Even when the reactor gases are harmless, they carry away a substantial amount of heat energy which must be replaced when the reactor vessel is fired up again for the next batch.
Two additional problems have been addressed by this invention: the continuous, though much reduced, loss of reactor vessel gas, and the fact that it is not always desirable to permit steam to enter the reactor. The leakage of reactor gas causes a loss of heat energy, and gas volume which must be replaced, or in those cases where the gas is the process product, a reduction in yield. It would be highly desirable to reduce further these extra operating costs, or eliminate entirely the loss of hot gases from the reactor.